This invention relates to containers for molten metal.
Many containers for molten metal are formed of a metal casing lined with refractory brick, e.g. high alumina bricks. These bricks are expensive, but as they prevent the molten metal attacking the metal casing their high cost is often justified. However, the bricks themselves are attacked, and this leads to a need to replace the bricks of the metal casing at frequent intervals, which is expensive, inconvenient and time-consuming. Monolithic linings suffer from similar disadvantages.
These disadvantages can be alleviated by applying a protective coating to the refractory lining. Coatings used up to now have not been wholly satisfactory because they have been ineffective to prevent damage to the refractory lining when skull is being removed from the vessel. Skull is solidified molten metal residue in the form of deposits adherent to the refractory lining.
According to the present invention there is provided a method of protecting a refractory lining in a molten metal container which comprises applying to the lining first a layer comprising particulate carbonaceous material, being free or substantially free from binding agent, and applying over that first layer a second layer of bonded particulate refractory material.
In this way, a duplex protective layer is produced, which acts effectively to prevent damage by skull adherence when the skull is stripped, the first layer containing the carbonaceous material acts as a parting layer enabling clean stripping of the skull, without damage to the underlying refractory lining.
The present invention may be used with all types of molten metal containers such as ladles, launders, tundishes and the like, lined with refractory bricks and with monolithic linings.